Bombay duck, (Harpadon nehereus), fish of the family Synodontidae, found in estuaries of northern India, where it is widely used as a food fish and, when dried, as a condiment. The Bombay duck grows to a length of about 41 cm (16 inches) and is a dull, translucent gray or brown in colour with small, dark speckles. It has a large mouth, a forked tail, and large pectoral and pelvic fins. Several related species, also belonging to the genus Harpadon, are found from Africa to Australia and New Guinea.